The present invention relates to a connecting device for use in a connecting of an external load which requires a power supply source.
In a tape recorder, for example, an external microphone is always utilized by connecting it to the tape recorder through a connecting device, instead of using a built-in microphone.
Conventional connecting devices include a plug member and a jack member as shown in FIG. 1 in which a plug member 1 has a sleeve 1a and a tip 1b. As shown in FIG. 2, the plug member 1 comprises the tip 1b, an insulator 1c provided therearound, the sleeve 1a provided therearound, lead wires 1e, 1f connected to the sleeve 1a and the tip 1b, respectively, and a pinch portion 1d for enveloping end portions of the sleeve, the tip, the insulator and lead wires therein. A jack member 2 comprises a contact segment 2a corresponding to the sleeve 1a of the plug member 1, and switching contact segments 2b, 2c corresponding to the tip 1b.
An external microphone 3 is connected between the sleeve 1a and the tip 1b of the plug member 1. The jack member 2 is provided on the housing of the tape recorder in such a manner that the contact segment 2a is connected to a built-in microphone 4 and to a ground, the contact segment 2b is connected to the microphone 4 and to a power supply source +Vcc through a resistor 5 and the contact segment 2c is connected to an amplifier 6. In such a connecting device, when the plug member 1 is inserted into the jack member 2 the switching contact segments 2b and 2c are disconnected so that the amplifier 6 is connected to the external microphone 3 instead of the built-in microphone 4.
A condenser or electrostatic microphone is generally utilized in a tape recorder so that the external microphone requires that a power supply source be connected to it, but in the above described connecting device it is impossible to directly supply the supply power to the external microphone 3 from the tape recorder. Then the external microphone 3 must have its own d.c. power supply source such as a battery 7.
Such connecting device has several disadvantages in that the external microphone has to be used by confirming the ON or OFF state of a power switch and the degree of power consumption of the battery resulting in troublesome operation, and the microphone becomes increased in weight resulting in complicated handling.